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Lucas Polynomial Sequence


A Lucas polynomial sequence is a pair of generalized polynomials which generalize the Lucas sequence to polynomials is given by

W_n^k(x)=(Delta^k(x)[a^n(x)-(-1)^kb^n(x)])/(Delta(x))
(1)
w_n^k(x)=Delta^k(x)[a^n(x)+(-1)^kb^n(x)],
(2)

where

a(x)+b(x)=p(x)
(3)
a(x)b(x)=-q(x).
(4)

Solving for a(x) and b(x) and taking the solution for a(x) with the + sign gives

 Delta(x)=a(x)-b(x)=sqrt(p^2(x)+4q(x))
(5)

(Horadam 1996). Setting n=0 gives

W_0^k(x)=Delta^k(x)(1-(-1)^k)/(Delta(x))
(6)
w_0^k(x)=Delta^k(x)[1+(-1)^k],
(7)

giving

W_0^0(x)=0
(8)
w_0^0(x)=2.
(9)

The sequences most commonly considered have k=0, giving

 W_n(x)=W_n^0(x)=(a^n(x)-b^n(x))/(a(x)-b(x)) 
=([p(x)+sqrt(p^2(x)+4q(x))]^n-[p(x)-sqrt(p^2(x)+4q(x))]^n)/(2^nsqrt(p^2(x)+4q(x))) 
w_n(x)=w_n^0(x)=a^n(x)+b^n(x) 
=([p(x)+sqrt(p^2(x)+4q(x))]^n+[p(x)-sqrt(p^2(x)+4q(x))]^n)/(2^n).
(10)

The w polynomials satisfy the recurrence relation

 w_n(x)=p(x)w_(n-1)(x)+q(x)w_(n-2)(x).
(11)

Special cases of the W(x) and w(x) polynomials are given in the following table.


See also

Chebyshev Polynomial of the First Kind, Chebyshev Polynomial of the Second Kind, Cyclotomic Polynomial, Fermat Polynomial, Fibonacci Polynomial, Jacobsthal Polynomial, Lucas Polynomial, Lucas Sequence, Pell Polynomial

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References

Horadam, A. F. "Extension of a Synthesis for a Class of Polynomial Sequences." Fib. Quart. 34, 68-74, 1996.

Referenced on Wolfram|Alpha

Lucas Polynomial Sequence

Cite this as:

Weisstein, Eric W. "Lucas Polynomial Sequence." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/LucasPolynomialSequence.html

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